The present invention relates to 4,5-dihydro-1H-1,2,4-triazole-3-carboxamide derivatives useful as active ingredient of herbicides and the herbicidal compositions containing such derivatives.
Rice, wheat and corn are the important farm products, and use of herbicides is essential for protecting these crops from harm by weeds to achieve an increased yield of the crops.
Few reports have been published relating to 4,5-dihydro-1H-1,2,4-triazole-3-carboxylic acid derivatives. Only disclosures relating to such derivatives were made in Japanese Patent Application Kokai (Laid-Open) Nos. 171475/86 and 210075/86 in which there are disclosed the compounds represented by the formula (I'): ##STR2## wherein X represents H, 3-CH.sub.3 or 4-Cl; R.sup.1 represents H; and R.sup.2 represents H, 4-Cl, 4-OH, 2-OH, 2-COOH, 3-CH.sub.3 or 3-OH.
In Japanese Patent Application Kokai (Laid-Open) No. 210075/86, mention is made of the herbicidal activity of the compounds represented by the formula (I'), but actually such compounds are unsatisfactory in their herbicidal effect. Thus, the development of a compound showing a high herbicidal activity and also having an effective selectivity in its action for killing weeds alone without doing any practical harm to the crops such as rice, wheat and corn has been strongly desired.
As a result of the present inventors' studies for providing a compound showing an excellent herbicidal effect and giving no practical harm to such crops as rice, wheat and corn, the present inventors found that the 4,5-dihydro-1H-1,2,4-triazole-3-carboxamide derivatives represented by the following formula (I) have an excellent selective herbicidal effect and achieved the present invention based on this finding: ##STR3## wherein R represents a straight-chain alkyl group having 1 to 10 carbon atoms which is non-substituted or substituted with 1 to 19 fluorine atoms or a branched alkyl group having 3 to 10 carbon atoms which is non-substituted or substituted with 1 to 19 fluorine atoms; X.sup.1 represents a halogen atom or an alkyl group having 1 to 3 carbon atoms; X.sup.2 represents hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms; Y.sup.1 represents hydrogen atom or fluorine atom; and Y.sup.2 represents hydrogen atom or fluorine atom.
The compounds represented by the formula (I) are different from the compounds of the formula (I') disclosed in Japanese Patent Application Kokai (Laid-Open) Nos. 171475/86 and 210075/86 in that the former have a side chain of --CH.sub.2 OR (wherein R represents the same as defined in the formula (I)) in the phenyl at the 1-position of 4,5-dihydro-1H-1,2,4-triazole, and are not found in the prior art literatures.
Thus, the object of the present invention is in providing the 4,5-dihydro-1H-1,2,4-triazole-3-carboxamide derivatives which have excellent selective herbicidal potencies, i.e., showing strong herbicidal activities against gramineous weeds and broadleaf plants, in particular, broadleaf plants, but quite hermless to the crops such as rice, wheat and corn, and the herbicidal compositions containing such compounds as active ingredient.